Review Question - QID 219463

This 21-year-old male suffered a right tibia fracture following a motor vehicle accident and successfully underwent tibial nailing. However, at ten months, he begins to experience pain at his fracture with evidence of hypertrophic callus. Initial management should include ruling out an infectious etiology prior to diagnosis of aseptic nonunion.

Tibia fractures are ubiquitous injuries in orthopedic trauma, being the most commonly seen long bone fracture. Despite an open fracture rate of approximately 20%, tibia fractures overall have excellent union rates, as nonunions are observed only 2-10% of the time. Tibia fractures are notorious for their slow healing rates, with the phenomenon being attributed to its subcutaneous location and relatively limited vascular supply anteriorly. As such, various methods have been developed to quantify bony healing, with the Radiographic Union Score for Tibial fractures (RUST) recently being popularized. Despite these adjunctive tools, the diagnosis of nonunion is still made on a individual basis, largely predicated on clinical progression/presentation. When considering a nonunion, ruling out septic nonunion prior to making the diagnosis of aseptic nonunion is crucial, as the former requires a vastly different treatment from the latter.

Wojahn et al. performed a retrospective review of 303 tibia fractures treated with reamed, statically locked intramedullary nails and applied the RUST method to assess bony healing. The authors note the presence of any bony healing was seen at an average of 8 weeks, with "radiographic union" being at 5 months. They further noted no implant failures occurred before 8 weeks. They conclude radiographs prior to the 8-week mark are of little clinical utility in the setting of a benign patient presentation.

Mundi et al. performed a retrospective cohort study nested within two multi-center, randomized controlled trials (Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures [SPRINT] and Fluid Lavage of Open Wounds [FLOW] trials) and applied the RUST method to analyze healing rates. The authors noted a significantly lower RUST score in nonunion patients compared to those who went onto union (4.8 vs 6.3) at 12 weeks, with scores of 4 at the three-month mark portending a 47% increase in absolute risk for nonunion. They also noted open fractures to be associated with risk for nonunion (OR: 4.76). The authors conclude the RUST method to be a beneficial tool in predicting nonunion in tibia fracture patients.

Bhandari et al. performed a multicenter, blinded randomized trial of 1,226 tibial shaft fractures who were randomized into either reamed (n=622) or unreamed (n=604) intramedullary nailing. The authors noted a 4.6% nonunion rate, all of which required implant exchange or bony grafting. Of the closed fracture group, the authors noted a significantly higher rate of primary events (fracture dynamization/auto-dynamization, screw removal, subsequent fasciotomy, hematoma drainage) in the unreamed group (17%) compared to the reamed group (11%), which was not reflected in those with open tibia fractures. Ultimately, the authors highlight the importance of reamed intramedullary nailing to mitigate risk for subsequent procedures in closed tibia fractures.

Figures 1 & 2 demonstrate orthogonal radiographs of a right short oblique mid-shaft tibia fracture. Figures 3 & 4 demonstrate orthogonal views of the tibia following intramedullary nail fixation. Figures 5 & 6 demonstrate hypertrophic callus of the tibia with a persistent radiolucent line.

Answers 1 & 3: CT scan and analysis of vitamin D levels would likely be the next steps if inflammatory markers were found to be negative
Answer 4: A bone stimulator could be attempted, however ruling out septic nonunion takes priority.
Answer 5: Scheduling the patient for exchange nailing would not be appropriate, as septic nonunion has not yet been ruled out.